The offset control on ZWO cameras used to be called 'brightness' - I have heard some talk that it was being disabled on certain models of camera, but I can't recall I noticed myself whether it was there or not when testing the new SDK.

If the brightness control is there then the brain will use it. If it isn't there but the sensor analysis data was done when the control was available then the results might be weird (certainly not something I planned for!). If the brightness has gone then I would suggest re-running sensor analysis and then the brain should work fine as it is capable of working with cameras with no offset control.

OK, I see "Brightness" in the Image controls (vs. camera controls). Thanks for clarifying that.

So back to Sensor Analysis, Smart Histogram, and Brain. In the Brain Results section I see Optimal gain but nothing about "Brightness" or offset, and when I hit apply, the gain changes but the Brightness does not.

Sorry, that's just inconsistent terminology in the brain dialog, which refers to this setting as 'black level'.

Unfortunately different camera manufacturers describe this as variously

* brightness
* offset
* black level

so it's hard for SharpCap to be consistent with all manufacturers.

Except for very high gains, SharpCap will usually end up setting this to zero - that's because SharpCap takes into account the effect of sky brightness in moving the histogram away from the LHS - usually sky brightness is quite sufficient for this and no additional boost is required.